Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
1998-09-23
2001-05-22
Beausoleil, Robert (Department: 2184)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C714S030000, C712S029000
Reexamination Certificate
active
06237113
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of initializing a control unit connected to a diagnostic bus.
BACKGROUND INFORMATION
In automotive engineering, for example, individual units are connected by a bus system (ISO 14230 Road Vehicle Diagnostic System) such as a data transmission line (K line, KWP 2000/Key Word Protocol 2000) over which the units communicate with an external automotive tester.
One example of such a unit is a vehicular airbag system, which has a control unit to deploy airbags in a motor vehicle if necessary on the basis of collision signals. The bus system connected to the control unit for this purpose has a diagnostic bus to detect any malfunction of the respective unit and to display the results.
To initialize or trigger a control unit connected to a diagnostic bus, the signals of the communication bus forming another part of an overall bus system containing the diagnostic bus are analyzed over the received data line or RxD line (RxD stands for received data line) of a microcontroller contained in the control unit. This is done on the basis of an initializing word or trigger word, in particular a 5-baud trigger word in two ways:
1) Sampling for high/low logic state is performed in a predetermined sampling cycle of preferably 10 ms. The corresponding information is read directly out of a port register (parallel interface register) of an interface between the control unit and the diagnostic bus.
2) The receive buffer register is read out and its status information is analyzed. Input is entered into the receive buffer register as soon as there is a transition from the high logic signal level to the low logic signal level on the bus, with the sampling of diagnostic information being performed by the bus interface receiver itself.
Initialization of the diagnostic bus achieved in this way (shown schematically in
FIG. 2
) is not reliable enough because there is no guarantee that the control unit connected to the diagnostic bus will be initialized or triggered unintentionally, e.g. by communication data from the tester or other stations.
SUMMARY OF THE INVENTION
According to the present invention, an initialization is reliably blocked or suppressed if the trigger word has not been recognized clearly or at all. In other words, the initialization is discarded and a new initialization is awaited if there is only one filled received byte having no framing error (stop bit 0 of the receive buffer register) during trigger word initialization (first criterion).
In an especially advantageous manner, after the end of the trigger word and until transmission of a speed synchronization pattern SSP, another monitoring interval is inserted and a check is performed to determine whether or not a transition from a high logic signal level to a low logic signal level is detected during this interval, with the initialization being discarded when this transition is detected due to a filled received byte. This is a second criterion with which it is possible to reliably prevent a control unit connected to the diagnostic bus from being triggered or initialized unintentionally.
A third criterion is that an initialization mode forming part of a traditional circuit for implementation of the diagnostic bus is switched to the “inactive” status as soon as the initialization procedure is concluded and a communication has started. This measure prevents interference from self-sent signals which might be interpreted incorrectly, and it guarantees that signals from other control units connected to the bus will not be interpreted as additional triggering or initialization.
REFERENCES:
patent: 4967344 (1990-10-01), Scavezze et al.
patent: 5304935 (1994-04-01), Rathke et al.
patent: 5526311 (1996-06-01), Kreifels et al.
patent: 5706297 (1998-01-01), Jeppesen, III et al.
patent: 5729169 (1998-03-01), Roohparvar
patent: 5790572 (1998-08-01), Oguro et al.
Baratz, Alan and Segall, Adrian, “Reliable Link Initialization Procedures”, Feb. 1988, IEEE Transactions On Communications vol. 36 pp. 144-152.
Beausoleil Robert
Kenyon & Kenyon
Robert & Bosch GmbH
Ziemer Rita A
LandOfFree
Method of initializing a control unit connected to a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of initializing a control unit connected to a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of initializing a control unit connected to a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2562840